Familial Cancer Syndromes

Question 1

what are caretaker genes

Answer 1

repairing DNA damage and metabolising carcinogens (preventing damage)

Question 2

what are gatekeeper genes

Answer 2

critical for regulating cell growth - decide on whether to apoptosis

Question 3

what are landscaper genes

Answer 3

control the surrounding stroll environment (eg blood supply)

Question 4

what are somatic vs germ line mutations

Answer 4

occurred in one cell in the body and formed tumour (somatic)

gremlin - inherited from parent so in every ell of body

Question 5

what is FAP

Answer 5

familial adenomatous polyposis (colon cancer)
mix of gremlin and somatic mutations
mutation in the APC gene, gatekeeper and tumour suppressor

Question 6

what is penetrance

Answer 6

the percentage of individuals with a given genotype who display the phenotype associated with that genotype

can be affected by genetic variation and environmental factors

Question 7

what isa tumour suppressor gene

Answer 7

gatekeepers which protect cells from becoming cancerous - loss of function increases risk of cancer

Question 8

what are oncogenes

Answer 8

regulate cell growth and differentiation

gain of function/activating mutations increase risk of cancer

Question 9

what is knudsons two hit hypothesis

Answer 9

sporadic mutations require both alleles of the gene to be mutated in order to cause cancer
ie both alleles of the tumour suppressor genes mutated to be inactivated

Question 10

why aren’t germline associated cancers present at birth

Answer 10

require an additional hit

Question 11

what type of studies can be done to find familial cancer genes

Answer 11

translocations, family studies, candidate gene analysis, whole exam sequencing

Question 12

what is the difference between sporadic and familial cancer

Answer 12

sporadic - onset at older age, one cancer, unaffected family members, rarely genetic, eg cervix, lung

familial - onset at younger age, multiple primaries in individual, affect family, genetically related cancers

Question 13

what are the purposes of genetic assessment

Answer 13

diagnosis of finlay history, risk of further cancers, screening, prevention, research

Question 14

what are some disadvantages of genetic assessment

Answer 14

anxiety, unhappiness, genetic discrimination, results may not lead to any change

Question 15

what is a retinoblastoma

Answer 15

childhood ocular cancer - very rare
familial so only takes one hit to be activated
Rb1 gene

Question 16

what is hereditary non-polyposis colorectal cancer

Answer 16

2-3% bowel cancers
polyps common
autosomal dominant
diagnosed by Amsterdam criteria

Question 17

what are the BRCA1 and BRCA2 genes

Answer 17

involved in DNA repair - caretaker genes

common mutation in jewish people, breast and ovarian cancer and increased risk of other cancers

Question 18

what is Li Fraumeni syndrome

Answer 18

P53 mutations - autosomal dominant
breast, sarcoma, brain
poor prognosis